Fast and frugal models of clinical judgement in novice and expert physicians

Our objective was to study whether “compensatory” models provide better descriptions of clinical judgment than fast and frugal models, according to expertise and experience. Fifty practitioners appraised 60 vignettes describing a child with an exacerbation of asthma and rated their propensities to admit the child. Linear logistic (LL) models of their judgments were compared with a matching heuristic (MH) model that searched available cues in order of importance for a critical value indicating an admission decision. There was a small difference between the 2 models in the proportion of patients allocated correctly (admit or not-admit decisions), 91.2% and 87.8%, respectively. The proportion allocated correctly by the LL model was lower for consultants than juniors, whereas the MH model performed equally well for both. In this vignette study, neither model provided any better description of judgments made by consultants or by pediatricians compared to other grades and specialties.

Isolation and preliminary biological assessment of AADGAPLIRFamide and SVPGVLRFamide from Caenorhabditis elegans

To date, 9 FMRFamide-related peptides (FaRPs) have been structurally characterised from Caenorhabditis elegans. Radioimmunometrical screening of an ethanolic extract of C. elegans revealed the presence of two additional FaRPs that were purified by reverse-phase HPLC and subjected to Edman degradation analysis and gas-phase sequencing. Unequivocal primary structures for the two FaRPs were determined as Ala-Ala-Asp-Gly-Ala-Pro-Leu-Ile-Arg-Phe-NH2 and Ser-Val-Pro-Gly-Val-Leu-Arg-Phe-NH2. Using MALDI-TOF mass. spectrometry, the molecular masses of the peptides were found to be 1032 Da (MH) and 875 Da (MH)(+), respectively. Two copies of AADGAPLIRFamide are predicted to be encoded on the precursor gene termed flp-13, while one copy of SVPGVLRFamide is located on flp-18. Synthetic replicates of the peptides were tested on Ascaris suum somatic muscle to assess bioactivity. ADDGAPLIRFamide had inhibitory effects on A. suum muscle strips, which occurred over a range of concentrations from a threshold for activity of 10 nM to 10 muM. SVPGVLRFamide was excitatory on A. suum somatic musculature from a threshold concentration for activity of 1 nM to 10 muM. The inhibitory and excitatory effects of AADGAPLIRFamide and SVPGVLRFamide, respectively, were the same for dorsal and ventral muscle strips as well as innervated and denervated preparations, suggesting that these physiological effects are not nerve cord dependent. Addition of ADDGAPLIRFamide (10 muM) to muscle strips preincubated in high-K+ and -Ca2+-free medium resulted in a normal inhibitory response. Peptide addition to muscle strips preincubated in Cl--free medium showed no inhibitory response, suggesting that the inhibitory response of the peptide may be chloride mediated. A normal excitatory response was noted following the addition of 10 muM SVPGVLRFamide to muscle strips preincubated in high-K+, Ca2+- and Cl--free media. (C) 2001 Academic Press.

Monozygotic twins discordant for phacomatosis pigmentovascularis: evidence for the concept of twin spotting.

The term phacomatosis pigmentovascularis (PPV) refers to the occurrence of vascular nevi with melanocytic or epidermal nevi. We report on monozygotic twins (MZTs) discordant for phacomatosis cesioflammea (PPV type II) providing evidence for the mechanism of twin spotting in the development of PPV. The affected twin had a nevus flammeus on the right arm and the right maxilla, and a pigmented area on the trunk in keeping with a persistent, aberrant Mongolian spot. The affected twin had bilateral ocular melanocytosis with abnormal scleral pigmentation, iris mamillations, increased pigmentation of the trabecular meshwork, and increased fundal pigmentation and secondary glaucoma. DNA testing confirmed monozygosity. This case of MZTs discordant for PPV supports the hypothesis that PPV results from mosaicism due to a post-zygotic mutational event and the concept of twin spotting.

Molecular testing of respiratory swabs aids early recognition of meningococcal disease in children

Early meningococcal disease (MD) diagnosis is difficult. We assessed rapid molecular testing of respiratory specimens. We performed genotyping of respiratory swabs, blood, and cerebrospinal fluid from children with suspected disease and nasal swabs (NSs) from matched controls. Thirty-nine of 104 suspected cases had confirmed disease. Four controls were carriers. Throat swab ctrA and porA testing for detection of disease gave a sensitivity of 81% (17/21), specificity of 100% (44/44), positive predictive value (PPV) of 100% (17/17), negative predictive value (NPV) of 92% (44/48), and relative risk of 12. NS ctrA and porA testing gave a sensitivity of 51% (20/39), specificity of 95% (62/65), PPV of 87% (20/23), NPV of 77% (62/81), and relative risk of 4. Including only the 86 NSs taken within 48 h of presentation, the results were sensitivity of 60% (18/30), specificity of 96% (54/56), PPV of 90% (18/20), NPV of 82% (54/66), and relative risk of 5. Swab type agreement was excellent (kappa 0.80, P

Structural characterisation and pharmacology of KHEYLRFamide (AF2) and KSAYMRFamide (PF3/AF8) from Haemonchus contortus

The FMRFamide-related peptides (FaRPs), KHEYLRFamide (AF2) and KSAYMRFamide (PF3) were structurally characterised from the parasitic nematode of sheep, Haemonchus contortus (MH isolate). Both peptides were sequenced in a single gas-phase sequencing run and their structure confirmed by mass spectrometry which identified peptides of 920 Da (C-terminally amidated AF2) and 902/918 Da (C-terminally amidated non-oxidised/oxidised PF3, respectively). AF2 had inhibitory effects on H. contortus muscle and inhibited acetylcholine (ACh, 10 mu M)-induced contractions, with a threshold for activity of I mu M. PF3 induced concentration-dependent contractions of H. contortus (activity threshold, 10 nM) and enhanced ACh contractions. Compared with the MH isolate, an isolate of H. contortus which has reduced sensitivity to cholinergic drugs (Lawes isolate) was less sensitive to the effects of PF3. The concentration-response curves for the cholinergic compounds ACh and levamisole (LEV), and PF3, but not a control, KPNFIRFamide (PF4), showed a statistically similar shift. This study implicates PF3 in the modulation of cholinergic function in H. contortus. (C) 1999 Elsevier Science B.V. All rights reserved.

Isolation, pharmacology and gene organization of KPSFVRFamide: A neuropeptide from Caenorhabditis elegans

To date, 53 peptides with C-terminal RFamides have been identified by the genome sequencing project in the nematode, Caenorhabditis elegans. In this study the FMRFamide-related peptide (FaRP) KPSFVRFamide (879.90 Da [MH](+)) was structurally characterized from extracts of the nematode, Caenorhabditis elegans. Two copies of KPSFVRFamide are encoded by a gene designated flp-9. RT-PCR identified a single cDNA product which was confirmed as flp-9 by sequence determination. Flp-9 cDNA was isolated from larval stages of C. elegans but was not detected-in adult worms, indicating that its expression is may be developmentally regulated. KPSFVRFamide displays sequence homology to the nematode peptide, KPNFIRFamide (PF4). The physiological effects of KPSFVRFamide, PF4 and the chimeras, KPNFVRFamide and KPSFIRFamide, were measured on body wall muscle and the vagina vera of the parasitic nematode, Ascaris suum. KPNFVRFamide and KPNFIRFamide had Cl--dependent inhibitory activity on innervated and denervated muscle-preparations, whereas KPSFVRFamide and KPSFIRFamide did not elicit a detectable physiological effect. Although all 4 peptides had inhibitory effects on the vagina vera, KPSFVRFamide and KPSFIRFamide (threshold, greater than or equal to 0.1 mu M) were less potent than KPNFVRFamide and KPNFIRFamide (threshold, greater than or equal to 10 nM). (C) 1999 Academic Press.

KSAYMRFamide (PF3/AF8) is present in the free-living nematode, Caenorhabditis elegans

To date, seven FMRFamide-related peptides (FaRPs) have been structurally characterized from C. elegans, of which one is structurally identical to the parasitic nematode peptide AF2 (KHEYLRFamide). The other six FaRPs have so far been identified in free-living forms only. in the present study an additional FaRP was isolated and structurally characterized from an ethanolic extract of C. elegans. The extract was screened using a C-terminally directed FaRP antiserum, and the FMRFamide-immunoreactive peptide purified to homogeneity using HPLC. Approximately 80 pmol of the peptide was subjected to Edman degradation and the unequivocal primary structure of the K-7-amide, KSAYMRFamide (PF3/AF8) was determined following a single gas-phase sequencing run. The molecular mass of the peptide was determined using a MALDI-TOF mass spectrometer and was found to be 919 (MH+), which is in agreement with the theoretical mass of C-terminally amidated PF3. A new flp-gene, designated flp-6, has recently been identified which encodes six copies of KSAYMRFamide (PF3/AF8). (C) 1998 Academic Press.

Isolation of AF2 (KHEYLRFamide) from Caenorhabditis elegans: Evidence for the presence of more than one FMRFamide related peptide-encoding gene

Numerous FMRF amide-related peptides (FaRPs) have been isolated and sequenced from extracts of free-living and parasitic nematodes. The most abundant FaRP identified in ethanolic/methanolic extracts of the parasitic forms, Ascaris suum and Haemonchus contortus and from the free-living nematode, Panagrellus redivivus, was KHEYLRF amide (AF2). Analysis of the nucleotide sequences of cloned FaRP-precursor genes from C. elegans and, more recently, Caenorhabditis vulgaris identified a series of related FaRPs which did not include AF2. An acid-ethanol extract of Caenorhabditis elegans was screened radioimmunometrically for the presence of FaRPs using a C-terminally directed FaRP antiserum. Approximately 300 pmols of the most abundant immunoreactive peptide was purified to homogeneity and 30 pmols was subjected to Edman degradation analysis and gas-phase sequencing. The unequivocal primary structure of the heptapeptide, Lys-His-Glu-Tyr-Leu-Arg-Phe-NH2 (AF2) was determined following a single gas-phase sequencing run. The molecular mass of the peptide was determined using a time-of-flight mass spectrometer and was found to be 920 (MH(+))(-), which was consistent with the theoretical mass of C-terminally amidated AF2. These results indicate that C. elegans possesses more than one FaRP gene. (C) 1995 Academic Press, Inc.

The technical merits of turbogenerating shown through the design, validation and implementation of a 1 dimensional engine model

Turbocompounding is the process of recovering a proportion of an engine’s fuel energy that would otherwise be lost in the exhaust process and adding it to the output power. This was first seen in the 1930s and is carried out by coupling an exhaust gas turbine to the crankshaft of a reciprocating engine. It has since been recognised that coupling the power turbine to an electrical generator instead of the crankshaft has the potential to reduce the fuel consumption further with the added flexibility of being able to decide how this recovered energy is used. The electricity generated can be used in automotive applications to assist the crankshaft using a flywheel motor generator or to power ancillaries that would otherwise have run off the crankshaft. In the case of stationary power plants, it can assist the electrical power output. Decoupling the power turbine from the crankshaft and coupling it to a generator allows the power electronics to control the turbine speed independently in order to optimise the specific fuel consumption for different engine operating conditions. This method of energy recapture is termed ‘turbogenerating’.

This paper gives a brief history of turbocompounding and its thermodynamic merits. It then moves on to give an account of the validation of a turbogenerated engine model. The model is then used to investigate what needs to be done to an engine when a turbogenerator is installed. The engine being modelled is used for stationary power generation and is fuelled by an induced biogas with a small portion of palm oil being injected into the cylinder to initiate combustion by compression ignition. From these investigations, optimum settings were found that result in a 10.90% improvement in overall efficiency. These savings relate to the same engine without a turbogenerator installed operating with fixed fuelling.

Electrostatic waves in superthermal dusty plasmas: review of recent advancement

Real plasmas are often caracterized by the presence of excess energetic particle populations, resulting in a long-tailed non-Maxwellian distribution. In Space plasma physics, this phenomenon is usually modelled via a kappa-type distribution. This presentation is dedicated to an investigation, from first principles, of the effect of superthermality on the characteristics of dusty plasma modes. We employ a kappa distribution function to model the superthermality of the background components (electrons and/or ions). Background superthermality is shown to modify the charge screening mechanism in dusty plasmas, thus affecting the linear dispersion laws of both low- and higher frequency DP modes substantially. Various experimentally observed effects may thus be interpreted as manifestations of superthermality. Focusing on the features of nonlinear excitations (solitons) as they occur in different dusty plasma modes, we investigate the role of superthermality in their propagation dynamics (existence laws, stability profile) and characteristics (geometry).

Strong electrostatic interaction effect on modulational stability of dust acoustic waves

The modulational instability of dust-acoustic waves is investigated, relying on a recently proposed model for strong electrostatic interactions between the highly charged dust particles. The resulting effect on the occurrence (threshold, growth rate) of modulational instability is investigated. Our results can in principle be tested experimentally.

Towards an automated evaluation process for software architectures

Optimizing and editing enterprise software systems, after the implementation process has started, is widely recognized to be an expensive process. This has led to increasing emphasis on locating mistakes within software systems at the design stage, to help minimize development costs. There is increasing interest in the field of architecture evaluation techniques that can identify problems at the design stage, either within complete, or partially complete architectures. Most current techniques rely on manual review-based evaluation methods that require advanced skills from architects and evaluators. We are currently considering what a formal Architecture Description Language (ADL) can contribute to the process of architecture evaluation and validation. Our investigation is considering the inter-relationships between the activities performed during the architecture evaluation process, the characteristics an ADL should possess to support these activities, and the tools needed to provide convenient access to, and presentation of architectural information.